BR data
ABB · ACS880
What does A794 mean?
One or more of the brake resistor data settings (parameters 43.08 … 43.10) are incorrect or missing. This prevents the drive from correctly calculating brake resistor operation and protection. Incorrect data can lead to improper braking or resistor damage.
Common Causes
- Brake resistor nominal resistance (`P43.08` (Brake resistor resistance)) or power (`P43.09` (Brake resistor power)) values are either `0` or outside the valid range.
- Brake chopper activation voltage (`P43.10` (Brake chopper ON voltage)) is set to an illogical or out-of-range value (e.g., below `DC bus undervoltage limit`).
- Typographical error during manual parameter entry via the control panel or PC tool.
- Corrupted parameter memory within the drive causing incorrect default or saved values for brake resistor data.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Retrieve the nameplate data from the physically installed brake resistor for its nominal resistance (Ohms) and rated power (Watts).
- 2
Enter the correct nominal resistance value into drive parameter `P43.08` (Brake resistor resistance).
- 3
Enter the correct rated power value into drive parameter `P43.09` (Brake resistor power).
- 4
Verify the brake chopper activation voltage `P43.10` (Brake chopper ON voltage) is set to a reasonable value, typically `700VDC` for a `400V` class drive.
- 5
If parameters were previously saved, try reloading a known-good parameter set from a PC tool (e.g., `DriveManager`).